Franciscus Elgersma was a Dutch Reformed minister of Oudkerk 1650, Leeuwarden 1652, Oudeschoot 1661, and Grouw after 1669. He was an ardent opponent of the Mennonites, whom he attacked both orally and in writings. In 1683 he charged Foecke Floris, the Mennonite preacher of Surhuisterveen who had preached in Grouw, with the heresy of Socinianism; when the States of Friesland did not take action against Foecke, Elgersma published a book dedicated to the States of Friesland, Rechtzinnige Leere van het Sacrament des H. Doops . . . teegen Socinianen, Papisten, Mennisten en andere Dwaalgeesten (Leeuwarden, 1685) and Kanker der Sociniaansche Ketterye (Leeuwarden, 1688). Foecke answered his antagonist by Beschermingh der Waerheyt Godts, of Schrijtuyrlijcke Verantwoording (Leeuwarden, 1687). Thereupon Elgersma published Seedige Verhandeling van de hooge Verborgentheit der H. Drieeenigheid (Leeuwarden, 1689). Then Elgersma was attacked by the anonymously published (the author was probably C. Stapel) Klaar vertoog, Dienende tot Wederlegginge van de ongefondeerde Beschuldigingen door Franc. Elgersma . . . tot last van Foeke Floris en andere Christenen, die hy Socinianen noemd (1689, n.p.). Meanwhile Foecke was arrested at Leeuwarden (1687), and banished from the province of Friesland (1688), but Elgersma, not satisfied that his enemy had been expelled, continued to warn about him and his pernicious doctrines in a Reformed Synod of 1689.